The feasibility of producing a set of microbeads (Quantitative Simply Cellular Calibration Kit) which can be used with a flow cytometer to directly quantitate the number of mAbs binding to specific populations of cells has been demonstrated. The objectives of this proposal are to improve the binding reactivity of the QSC microbeads, evaluate new methods of calibrating the binding sites of the microbeads and determine the precision and accuracy of measuring mABs binding to cells by this new methodology. An instruction manual and computerized analysis worksheet will be developed to support this kit. The QSC Calibration Kit and support materials will be initially evaluated by three outside investigators, followed by a more general evaluation via a workshop and sample distribution at the Clinical Cytometry Meeting in Charleston, SC. The development and commercialization of this methodology will provide clinical and research laboratories with a powerful and innovative diagnostic tool. Being able to quickly and accurately determine the number of mAbs binding to specific cell populations will help pathologists, immunologists and oncologists to achieve more accurate diagnosis, treatment and prognosis of immune related diseases, such as AIDS.